Regulation of Aberrant Protein Production

摘要 有缺陷的蛋白质是由突变、转录错误、应激和其他因素引起的。这些异常 蛋白质通常是有毒的并引起许多人类疾病。质量控制（QC） 细胞中的途径：缺陷mRNA的无义介导、不停和不去衰变， 泛素/蛋白酶体系统已经合成的错误折叠的蛋白质。最近，我们发现了一个新的QC 异常蛋白质产生调节（RAPP）。RAPP是一个先发制人的QC，它监测 蛋白质在核糖体合成过程中，感觉有缺陷的蛋白质并降解其mRNA模板。 这是第一个将异常蛋白质的信息转移到mRNA降解机制的例子。 通常，从核糖体出口通道出现的新生多肽与靶向或折叠因子相互作用。 当突变阻止了这些相互作用时，Ago 2蛋白，RAPP反应中的传感器，检测到突变。 这些重要的相互作用的丧失并触发mRNA降解。令人惊讶的是，Ago 2内切核酸酶活性 在这个过程中是不需要的。因此，RAPP的分子机制还没有很好地理解， 了解其mRNA降解机制及其底物。拟议的项目将填补这些空白， 知识我们的假设是RAPP是一种通用的蛋白质质量控制途径，由三个组成 主要步骤：检测异常新生链复合物，翻译抑制， 用于降解异常mRNA的特化细胞质病灶。我们的具体目标是为了测试这一点 假设，并致力于（1）阐明蛋白质表达下调的机制， RAPP，和（2）确定RAPP是否是一个一般机制的蛋白质质量控制的分泌和 哺乳动物细胞膜蛋白。该建议涉及在体内和体内的综合应用， 体外方法，包括我们独特的技术，iPINCH，用于鉴定与 新生锁链。确定RAPP的作用范围和作用机制将对蛋白质质量控制领域产生重要影响 通过提供对细胞防御错误和潜在毒性的更好理解， proteins.

ABSTRACT Defective proteins result from mutations, mistakes of transcription, stress, and other factors. These aberrant proteins are often toxic and cause a number of human diseases. There are several quality control (QC) pathways in the cells: nonsense-mediated, no-stop, and no-go decays for defective mRNAs, and the ubiquitin/proteasome system for already synthesized misfolded proteins. Recently, we discovered a new QC pathway called Regulation of Aberrant Protein Production (RAPP). RAPP is a preemptive QC, it monitors proteins during their synthesis at the ribosome, senses defective proteins and degrades their mRNA templates. It is the first example of transferring information about aberrant proteins to mRNA degradation machinery. Normally, nascent polypeptides emerged from the ribosome exit tunnel interact with targeting or folding factors. When a mutation prevents these interactions, the Ago2 protein, a sensor in the RAPP response, detects the loss of these important interactions and triggers mRNA degradation. Surprisingly, Ago2 endonuclease activity is not required in the process. Thus, the molecular mechanism of RAPP is not well understood, very little is known about its mRNA degradation machinery and its substrates. The proposed project will fill these gaps in knowledge. Our hypothesis is that RAPP is a general protein quality control pathway that consists of three major steps: detection of an aberrant nascent chain complex, translational repression, and formation of specialized cytoplasmic foci for degradation of the aberrant mRNA. Our specific aims are designed to test this hypothesis and directed to (1) elucidate the mechanism by which protein expression is down-regulated in RAPP, and (2) determine whether RAPP is a general mechanism of protein quality control for secretory and membrane proteins in mammalian cells. The proposal involves application of comprehensive in vivo and in vitro approaches, including our unique technology, iPINCH, for identification of Proteins Interacting with Nascent Chains. Determining the scope and mechanism of RAPP will impact the field of protein quality control research by providing a better understanding of cellular defense against erroneous and potentially toxic proteins.